• seal & sea lion
Their rear flippers can be rotated forward and their front flippers are really strong so they can stand up and walk on all four flippers on land.
http://qindex.info/i.php?x=6929

• walk on all four flippers
Their rear flippers can be rotated forward and their front flippers are really strong so they can stand up and walk on all four flippers on land.
http://qindex.info/i.php?x=6923